1. Field of the Invention
The invention relates to temporary repair of telephone networks when a pair of wires between a field cable service box and the central telephone switching office has become defective. Due to the specialized nature of telephone transmission, those skilled in the art are those individuals that have day to day responsibility for the installation and maintenance of the nation's regional telephone networks. Specific reference is made to the standard operating procedures employed by the various regional operating companies. More specifically, the field of the invention relates to those telephone networks which employ a distributing frame having protector blocks.
2. Discussion of the Prior Art
A grave problem which plagues the telephone system, affecting both economic return and customer satisfaction, isthe repair of defective wire pairs. Pairs of wires which have been damaged between field service boxes, such as, the terminal or cable closures i.e. pedestals serving the subscriber's premises and the central office often disrupt service to the customer. Such disruptions or lack of total service can last from four to eighteen hours. (Over 30% of the disruptions are not solved within eight business hours.)
The disruption of telephone service for long periods creates severe customer dissatisfaction. It also disrupts trade and commerce since no communication is possible. The lack of telephone service obviously can create dangerous conditions since the customer is precluded from communicating with emergency personnel.
Disruptions due to defective cable pairs are not isolated incidents. In the Dallas telephone region during the period from Apr. 1, 1983 to Apr. 1, 1984, there were approximately 58,500 incidences of loss of service due to single cable pairs going defective. The number of such incidents nationwide is in the millions and the cost to restore service typically is $216.25 per incident. The national cost of this problem is hundreds of millions of dollars.
The telephone network basically comprises pairs of wires which connect the premises of individual customers to a central office. FIG. 1 traces the path of a pair of wires from a customer's premises in the field to a central telephone switching office.
The wires known as the station wires from the customer premises 10 are attached through a protector or arrestor, which bleeds off high voltages, to a pair of wires known as a service wire or "drop" 12. The two wires which comprise the service wire 12 are referred to as the "tip" 14 wire and the "ring" 16 wire. The service wire 12 runs from the customer premises to a field service box 18, such as, a terminal located on a pole if the cables are aerial or to a cable closure or pedestal which sits on the ground if the cables are buried. The "tip" 14 and "ring" 16 wires are the basic wires of the network.
A terminal or cable closure 18 as shown in FIG. 2 has a number of sets of posts 20. Each set of posts 20 is attached to a pair of wires that together form the cable 28. The service wire 12 from the customer premises is connected to a particular pair of posts as per the assignment of the telephone company. More than one customer may use the same terminal or cable closure 18. However, each customer's service wire 12 is attached to its own assigned set of posts 20. If a customer's service wire 12 is not attached to the correct posts, they will not be able to receive or transmit telephone calls since the telephone company computer will be sending their calls through the wrong pair of wires.
The wire pairs from a terminal or cable closure join other pairs of wires to form a cable 28. The cable 28 is intercepted at various points by other terminals and cable closures 18 in order to allow the wires from additional customers to join in the use of the cable. Wires from the cable are attached to the posts 20 of these terminals and cable closures 18. In order to provide flexibility to the network a wire pair may be attached to posts at one or more terminals or cable closures. Thus, it is important for the technician to know whether a pair of wires is in working condition and whether another customer is using said pair before attaching a customer's service wire to a particular pair.
Usually the cable that passes through a line of terminals or cable closures joins other cables 28 at a field service box which is referred to as a "servicing area interface" 24. Each pair of wires from each of the cables is attached to a pair of posts. These posts are wired to a second set of posts which are connected to pairs of wires from a larger cable 26 that goes to the telephone company central office 30. Cable 26 may pass through additional field service boxes 24. Again it is important that the proper posts be wired together to insure that the customer receives their telephone calls and dial tone. These field connector boxes are usually readily accessible to technicians and therefore provide a preferred location for switching customer pair assignments.
The wire pair may have a load coil, or inductors attached which negates transmission losses prior to entering the telephone company central office 30. A typical cable entering a central office has 2100 pairs. A rural central office will have far fewer pairs, whereas, a large city central office will have a large number of pairs and cables. In the basement or vault of the central office the cable is spliced to the central office wiring.
As shown in FIG. 3 the wire pairs are strung from the basement 32 to a distributing frame 34 which is on an upper floor of the central office. This frame has a vertical 36 and horizontal 38 component. Located on the vertical component of the frame are protector blocks 40 containing a protector for each wire pair. The purpose of the protector blocks 40 is to protect the central office equipment from excessive voltage or current surges. The frame is a metal support structure having protector blocks 40 mounted on its front face. The protectors have metal prongs which plug into the front of the blocks and connect the wire pairs from the field that have entered the central office to jumper wires 42 that connect the incoming field wires to the horizontal component 38 of the distributing frame 34. The vertical component 36 of the frame 34 is the terminating point of the outside or field wire pairs from cable 26.
The horizontal component 38 of the distributing frame 34 is the basic frame of the central office 30. All of the central office wire pairings are contained on this frame. Although two wires may have been adjacent in a cable they could be widely separated on the frame. This is to allow the even distribution of the circuit usage to the switching equipment. These frames can be hundreds of feet long and contain thousands of wires. The horizontal component of the frame is a series of vertically stacked horizontal supports or shelves upon which the wires are laid. The shelves contain posts upon which the jumper wires 42 from the vertical component 36 of the frame are attached. The posts containing the jumper wire pairs are then attached to a second set of posts which have corresponding wire pairs attached for permanent connection with the switching equipment.
The distributing frame 34 thus provides a means to associate through cross-connect wiring any of the thousands of possible combinations of cable wire pairs to office switching equipment. As in the field, it is important that the customer's wires be attached to their assigned posts. It is very difficult to trace stray wires on the horizontal component 38 of the frame since there are hundreds of wires lying on each of the frame's horizontal shelves or supports. As would be expected the design, sizes and numbers of these distributing frames vary depending on the switching office size, type of switching equipment, features etc.
A problem arises when a pair of wires becomes defective in the field and a loss of service results. The customer reports the loss of service. This report is general, "I don't have dial tone" or "I cannot be called." The telephone company dispatches a repair technician to determine the location of the damage and restore service. Under the present system the customer usually will not have service restored for four hours from the time the technician arrives.
The traditional method for solving cable problems requires the field technician to coordinate the activities of the repair procedure. This is a very inefficient manner of solving cable problems since the technician has limited knowledge of the intricate cable route and limited equipment. Another problem is that the telephone companies have grown so large that they have been required to segregate different functions in different departments. It can be difficult for a technician in the field to coordinate with all of the various departments involved in a defective cable situation. Breaks that occur in rural areas are especially expensive since not only must a field technician be dispatched but, since the central offices are usually not manned, a central office technician must also be sent.
Briefly, when a technician reaches the premises of a nonworking telephone he checks the cable pair to determine where the trouble has occurred. If the break has occurred between a field service box, such as, a terminal, cable closure, or "servicing area interface" and the central office and cannot be readily repaired, then the customer must be connected to a new set of wire pairs. This transfer usually occurs at the "servicing area interface" box. In many cases defective wire pairs are not repaired until a later date since it is not economical to isolate each wire pair fault and repair it. The telephone company normally waits until there is a number of repairs to be made on a cable and then repairs all at one time. Also, the out of service time until a wire fault is located and repaired can be several days. Therefore, the normal procedure is to abandon the defective wire pair and connect the customer to a different functioning vacant pair which is available in the same field connection box.
Transferring a customer to a new cable pair requires the efforts of several departments. If all of the relevant company units are not consulted about the change, the customer might not receive its telephone calls or could be disconnected. All of the telephone company computers, records and switching equipment must be revised to contain the new routing prior to implementation of the change.
A typical repair procedure is as follows:
1. Technician calls the records center to ascertain which pairs, in the field connection box, services the customers and attempts to locate fault with ohm meter.
2. If technician cannot repair trouble, he again calls the record center to obtain vacant functioning wire pairs for testing.
3. The technician then calls the distributing frame personnel in order for them to jointly test the vacant pairs to insure that they will work.
4. The technician must then call the maintenance center for authority to switch the customer line or "drop" to a vacant pair.
5. After receiving authority to switch pairs the technician calls the records center to notify them of the change so that they can begin revising manual and computerized records to reflect the use of the new pair.
6. The technician removes the customer wire from the old cable pair and attaches it to the new cable pair in the field.
7. Following the transfer the technician contacts the frame personnel to make necessary changes.
8. Technician notifies central office administration center to make necessary software computer changes in the central office switching equipment.
9. The technician then notifies the maintenance center that the transfer has been completed in the field and leaves the customer's premises. Dial tone has not been restored. (165 minutes have elapsed.)
10. The frame personnel then receive the necessary information from the computer system to connect the new cable pair with the switching equipment and disconnect the old cable pair. (total time 225 minutes)
There have been a number of attempts in the past to solve the problems encountered by the above method. Numerous attempts to solve the problem have been suggested, tried and have failed in efforts to reduce total duration time required of all involved work groups to restore service in the previous methods. However, all of these attempts have involved changing the connections on the distributing frame and still required changing records and distributing these changes before any work would begin, the administrative chain of events that must occur with the old procedure has never lended itself to successful revisions to reduce restoral time.
It is natural to assume, since actual changing of the pairings takes place at the distributing frame, that this would be the most likely spot to attempt to modify the procedure. Instead others have learned that the nature of the horizontal component of the distributing frame does not lend itself for an improvement of the procedure. This is due to the size of the frame, the location of the pairings, and manner in which the wires are connected. The pairings as they come from the vertical component of the distributing frame are not placed adjacent but can be separated by hundreds of feet and each wire is individually connected. Also, the beginning of the office wiring is located on the horizontal component of the distributing frame. Since the wire pairs entering the protector blocks are considered field wires and are permanent wiring, it would not be logical to make changes in the office wiring at this location.
The present invention is advantageous in that it is more economical than traditional methods and it places the customer back in service faster. It is also advantageous in that it allows each function to be performed by the department most proficient at that task and for control of the repair operation to be vested in the central office. A further advantage is that it allows certain tasks to be performed during slack periods. Still other advantages include greater reliability that service will be restored promptly, fewer missed appointments, fewer callbacks, and greater technician productivity. The device of the invention is advantageous in that it is simple to operate and inexpensive. Another advantage of the device is that it allows implementation of simplified repair procedures.